Where are you located? I have both a One M8 and S5 (personal and work) on AT&T, but neither has found the update. My assumption is this will be a gradual roll-out from region to region, meaning we don't ALL get it at once?
Nice! Sounds like this was a necessary "bridge" to Lollipop. I'm still waiting for the update, unfortunately. No dice even when checking manually through the settings menu. Oh well, I guess it has to come at SOME point?!